Method and apparatus for cold forming elbows from tori

ABSTRACT

An apparatus for forming a half torus of a desired cross section from an annular flat plate. Flanging means are provided which bend the outer edge of the annular plate to shape the plate into a large shallow inverted cup to prevent wrinkling of the plate during subsequent forming. Cold forming means then engage the flanged plate to form the half torus by the drawing of a smaller, deeper cup from a larger shallower one.

United States Patent 1191 Garner et al. Apr. 9, 1974 [54] METHOD AND APPARATUS FOR COLD 165,302 7/1875 Butler 113/116 UT FORMING ELBOWS F TORI 1,690,523 11/1928 Bell 72/348 3,137,067 6/1964 Bruecker 72/347 [75] Invent rs: n th Garner; Jam s R- 2,739,557 3/1956 Staubitz 72/348 Martin; Jack C. Smith, all of Chattanooga, Tenn. FOREIGN PATENTS OR APPLICATlONS [73] Assigneez Cumbustion Engineering, Inc" 355,286 6/1922 Germany 29/463 Windsor, Conn.

I Primary Examiner-Richard J. Herbst [22] 1973 Attorney, Agent, or Firm-Eldon H. Luther [21] Appl. No.: 333,939

Related US. Application Data 57 S C 2 D' 1 9, [6 1 of Ser No 213 607 Dec 2 1971 An apparatus for formmg a half torus of a deslred 52 US. Cl. 72 344 72 348 Cmss Section annular Hanging E5 Int. l {d means are provided which bend the Outer edge Of the [58] Field of 72/347 annular plate to shape the plate into a large shallow 157 1 i 16 inverted cup to prevent wrinkling of the plate during subsequent forming. Cold forming means then engage 56] References Cited the flanged plate to form the half torus by the drawing UNITED STATES PATENTS of a smaller, deeper cup from a larger shallower one.

235,353 12/1880 Geldreich 72/347 4 Claims, 6 Drawing Figures PATENTEB APR 9 ISM SHEET 1 0F 3 FIG. 2

METHOD AND APPARATUS FOR COLD FORMING ELBOWS FROM TORI This is a division, of application Ser. No. 213,607 filed Dec. 29, 1971.

SUMMARY AND BACKGROUND OF INVENTION This invention pertains to the art of manufacturing pipe bends, and more particularly to a process of cold forming pipe bends of large diameter and thin wall thickness from annular flat plates.

There is a need for large diameter elbows to turn corners in fuel pipelines of steam generators and for many other purposes. Such elbows may be needed in a variety of angles (degrees) up to 180. Most commonly, elbows are hot formed in 90 increments from segments of straight pipe using expensive, specialized equipment and dies. The pipe used for making such elbows is expensive. Furthermore, much waste is incurred when one or more elbows less than 90 elbows (as is currently done). In order to minimize the great cost of making such pipe bends, this invention presents a new method of manufacturing therefor. This invention involves a method of making elbows of various angles by first welding identical tori halves together to form a full torus, the tori halves having been cold formed from flat annular plates, and then cutting the full toms to make several pipe bends of desired angles.

Some of the advantages of this method over the conventional method of hot forming 90 bends from segments of straight pipe are as follows: 1) less waste is involved in cutting various combinations of elbow degrees from a 360 torus versus a 90 elbow; 2) time requirement of large press or other large equipment is minimized because the number of pieces formed is greatly reduced; 3) elbows are made from relatively inexpensive plate rather than pipe; 4) tori halves formed by an identical process on the same symmetrical dies are identical and therefore easy to fit together; and 5) because the welds are continuous circles, the assembly can be economically welded together by a continuous process while the assemblies are being turned under an automatic welding head by a weld positioner-rotator.

The idea of cutting elbows from welded tori halves is not a new concept as may be seen in U. S. Pat. Nos. 3,550,253 and 2,335,887. The first patent cited involves the manufacture of tori halves by casting and the second patent discloses a method for hot spinning of tori havles. The process of cold forming the tori halves is distinctly different from the patented processes and also provides several advantages over the disclosed processes.

In cold forming, the tori halves are not subjected to the flaws as experienced in casting, thereby avoiding the waste of scrap material which is inherent in being unable to utilize the full 360 torus for the cutting of elbows. Furthermore, the two tori halves in being cold formed by an identical process on the same symmetrical dies are each identical rather than the possibility of each being different as would be the case with casting tori halves. Castings have to be machined in order to be comparable in precision to cold formed parts. Thus the cold formed tori halves are easier to fit together.

The advantages of cold forming over hot spinning of tori halves are dimensional stability and decreased expense. Inherent in hot spinning is the inability to accurately predict the final cooled dimensions of a formed toroidal dish brought about by non-uniform cooling processes and inaccurate final temperature control. As previously mentioned, the cold forming of half tori will yield identical elements, whose dimensions can easily be ascertained, thereby avoiding the dimensional problems of hot spinning. Furthermore the cold forming of half tori does not involve the added expense of heating flat plates, cooling heated dishes and moving components from one process to another.

The inventive method of cold forming identical tori halves is accomplished by the following procedure. An annular flat plate or blank is placed on the bottom female die of a cold forming apparatus. The blank is first shaped into an inverted cup in order to prevent wrinkling of the plate during subsequent forming; that is, a flange is formed onto the outer edge of the plate. Next, in the same press stroke the half tori is formed by the drawing of a smaller, deeper cup from the large, shallower one. Thus, in this way the forming time and number of pieces of equipment necessary to form the tori halves is greatly reduced, while the quality of the work is enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a half torus utilized in the invention;

' FIG. 2 is a sectional view of a full torus taken on a plane through the logitudinal axis of the torus;

FIG. 3 is a sectional view of a cold forming die apparatus before forming has taken place; I

FIG. 4 is a sectional view of the cold forming die apparatus of FIG. 3 after flanging has taken place;

FIG. 5 is a sectional view of the cold forming die apparatus of FIG. 3 after a half torus has been formed; and

FIG. 6 is a sectional view of the bottom die with the half torus being ejected from the die.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters are used to designate like ele'ments, FlG. 1 shows a finished, cold formed half torus of the invention, generally designated 10. The half torus 10 has an inner welding edge 12, an outer welding edge 14, and an annular channel 16 which in FIG. 1 is of semicircular transverse cross-section but may be of any selected cross-section. A full torus, generally designated 27, is shown in FIG. 2 and is formed by integrally joining two identical half tori 10. This can be accomplished by welding the two half tori 10 together along the inner welding edge 12 and outer welding edge 14 to form welded seams 28 and 30. After welding is completed the full torus 27 can be cut to form several pipe bends of desired angle or angles so as to use the full 360 of a torus. Although the cutting of the tori halves is done after they are welded together, for illustrative purposes, FIG. 1 shows several proposed cutting lines 18. The cutting lines 18 are selected so that the full 360 torus will be utilized. As seen in FIG. 1, the cutting lines 18 define the sectors 20, 22, 24, and 26 and, after the welding has taken place, will define pipe bends with bend angles of 120, 45, and respectively. Usually, the cold formed pipe bends have a finished pipe diameter of 18 inches to 26 inches and a wall thickness of about one-half inch. The bend radius to the pipe center is normally two times the pipe diameter. As is apparent, the full 360 of the formed torus may be used to furnish several different types of pipe bends. This saves greatly in the expense of materials and the time required to manufacture pipe bends.

In the cold forming of a half torus, FIGS. 3 to 6 inclusive show a die apparatus 31 in various stages of reducing a flat annular plate to a half torus. More particularly FIG. 3 shows a circular female die member 32 attached to a base or lower platen 34. The die member has an outer cylindrical surface 36 which extends upward from the platen 34 and terminates in a rounded shoulder 38. Disposed radially inward from the cylindrical surface 36 are two cylindrical surfaces 42 and 48 which form the sides of an annular cold forming channel 40 concentrically located with respect to the outer cylindrical surface 36. The outer cylindrical surface 42 of the annular channel 40 extends upward and terminates in a rounded shoulder 44, the rounded shoulders 44 and 38 thus forming a rounded flanging and cold forming lip 46. The inner cylindrical surface 48 of the channel 40 also extends upward from the platen 34 and terminates in the rounded shoulder 50. The mean radius of the channel 40 is substantially equal to the desired mean radius of the finished half torus. The two cylindrical surfaces 42 and 48 of the channel are spaced from each other a distance equal to the radial distance between the inner and outer edges of the desired half torus.

Spaced radially inward from the shoulder 50 of the die 32 and merging therewith is a horizontal upper surface 52. Protruding upward from the upper surface 52 is an annular ring 54 which is displaced radially inward from the inner cylindrical surface 48 and which is concentrically positioned with respect to the cylindrical outer surface 36 and the annular channel 40. The outside surface 56 of the ring defines a locating surface for the flat circular plate blank P which is to be cold formed. The blank P has a concentrically circular cutout of a radius substantially equal to the outside radius of the annular ring 54 such that when the blank is disposed on the die as shown in FIG. 3, it will rest on the upper surface 52 and on the top edge of the lip 46 and be retained in position by the locating surface 56. Also, as will be apparent herein below, the annular blank P must have an outer diameter greater than the diameter of the outer cylindrical surface 36 of the die 32.

The male die member generally designated 58 is cylindrical in shape and is attached to an upper platen 60. The die 58 comprises two annular rings 62 and 64 cffectively connected to one another. The outer ring or flanging plunger 62 extends downwardly from the platen 60, the inner cylinder surface 66 and outer cylindrical surface 68 of the plunger 62 terminating so as to form a flanging lip 70 with a rounded inner shoulder 72. The inside radius of the flanging plunger 62 must be slightly greater than the outside radius of the cylindrical surface 36 of the die 32 by an amount approximately equal to the thickness of the plate blank P so as to permit proper forming operations in the manner to be described below. The inner annular ring or cold forming plunger 64 is disposed radially inward from the flanging plunger 62 and extends downwardly from the plate a distance less than that of the flanging plunger 62. The inner cylindrical surface 74and outer cylindrical surface 76 of the cold forming plunger 64 terminate in a cold forming lip 78 with a forming surface 80 whose cross-section is the same as that of the desired formed half torus. As depicted in the figures, the crosssection is semi-circular and thus the formed half torus will have a channel of semi-circular cross-section. The mean radius of the forming plunger 64 is equal to the desired mean radius of the formed half torus.

The cold forming plunger 64 is positioned and of such a shape that it may enter the annular cold channel 40 of. the female die member 32. The cylindrical surfaces 74 and 76 of the plunger are spaced a distance equal to the spacing of the cylindrical surfaces 42 and 48 of the annular channel 40 plus approximately twice the thickness of the plate blank P which is to be formed.

A means for removing the finished half torus from the cold forming die apparatus 31 has been shown in FIGS. 3 to 6 inclusive and has been generally designated as an ejection means 82. To facilitate the positioning of the ejection means 82 beneath the female die member 32, the bottom of the annular channel 40 and a part of the female die member 32 have been cut away. The ejection means 82 includes an actuating shaft 84 which is located at the central axis of the cylindrical female die 32 and extends downward through a hollow opening 86 in the lower platen 34. Adjacent to the upper end of actuating shaft 84 and extending perpendicularly to the axis thereof are several interconnected spider arms 88, which may be spaced equally about the circumference of the shaft 84. The arms 88 extend radially outward so that the outermost extremity lies directly beneath the annular channel 40 which has been cut away. Attached to the top of the spider arms 88 and positioned at the outermost extremities of the arms are pads or blocks 90 which will be used to eject the formed half torus from the annular channel 40 (see FIG. 6). At least three interconnected spider arms 88 are necessary so as to balance the torus as it is pushed out of the channel.

The series of operations incident to the cold reduction of a flat annular plate P to a half torus, and as illustrated in the Figures to which reference has hitherto been made, will now be described. With the upper platen 60 elevated above the lower platen 34,'a flat circular plate P with a concentrically circular cutout is first placed over the locating surface 56 allowed to rest on the upper surface 52 and the rounded lip 46. The platen 60 is then lowered by means of a press (not shown) so that the flanging plunger 62 contacts the flat plate P at the contact point 92 as shown in FIG. 3. The male die 58 is then depressed further so that the rounded shoulder 72 of the flanging plunger 62 forces the flat plate to be cold formed about the outer rounded shoulder 38 of the lip 46 on the female die 32. Thus the flat plate P has been formed into a large shallow cup P as depicted in FIG. 4 with downward turned flanged edges 94. This operation is performed so as to prevent wrinkling during the subsequent forming without the need of a blank holder. With the male die 58 having descended so that the forming plunger 64 contacts the large shallow cup P at contact point 96 (see FIG. 4) the die is further depressed so that the plunger 64 forces the cup P' into the annular channel 40. As the plunger 64 enters the channel 40 the cup P is cold formed about the forming surface of the plunger 64 and about the rounded shoulder 44 and 50 of the annular channel 40 thereby causing the large shallow cup P to be cold formed into the smaller,

deeper inverted cup of the half torus P" as depicted in FIG. 5. The male die member 58 is then removed from the channel 40 and the actuating shaft 84 of the ejection means 82 forces the interconnected spider arm 88 upward so that the pads 90 contact the half torus at 98 and push it upward out of the channel 40. The inside edge 100 and outside edge 102 of the formed half torus P" are then finished and prepared for welding thus completing a cold formed half torus such as that designated as in FIG. 1.

By this novel method of cold forming, a flat plate blank is reduced to a half torus in just one press stroke. As is apparent, this reduces the time that presses are tied up and also reduces the cost and necessity of equipment since the half torus is completely cold formed on one simple press. Also since each half torus will be formed from the same die apparatus, each will be identical and therefore easy to fit together and weld. Finally, since the half torus is cold formed, the dimensions of the die member can easily be ascertained to yield a half torus of desired dimensions. None of these advantages are present when the fiat plate blank is hot formed to a hlaf torus since the forming takes place when the plate is hot and therefore presents the difficulty of accurately predicting the final dimensions of the formed half torus.

While I have illustrated and described a preferred embodiment of my invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What is claimed is:

1. An apparatus for cold forming a half torus of desired transverse cross-section from an annular flat plate comprising: a first base; a second base spaced from said first base; and actuating means for moving said first base toward said second base; a male die member attached to and extending from said first base toward said second base, said male die member comprising an annular flanging means for flanging said annular flat plate, and an annular cold forming means for forming said plate into a half torus of said desired cross-section, said annular cold forming means disposed radially inward from said annular flanging means and integrally related thereto, said annular flanging means being of longer transverse height-from said first base than said annular cold forming means; a female die member attached to said second base and extending toward said first base, said female die member comprising a cylindrical outside surface positioned so as to permit said annular flanging means of said male die member to pass along the outside thereof, a receiving means for receiving said annular cold forming means of said male die member, and a means for locating and retaining said annular flat plate whereby when said bases are actuated, said male member and said female member engage one another such that said annular flanging means passes outside of said cylindrical outside surface and said annular cold forming means of said male member enters said receiving means of said female member, thereby causing said flat plate to be first flanged and then formed into said half torus of said desired crosssection in a single action step.

2. An apparatus for cold forming a half torus of desired transverse cross-section from a flat annular plate comprising:

a first base;

a cylindrical female die member extending from said first base, said female die member having integrally related elements including a cylindrical locating surface for locating and retaining said flat plate, two cylindrical surfaces defining an annular channel of width substantially equal to the width of said desired transverse cross-section of said half torus and positioned radially outward from said locating surface, and a cylindrical outer surface positioned radially outward from said locating surface and from said annular channel;

a second base;

a cylindrical male die member extending from said second base, said male die member having integrally related elements including a first annular plunger for cold forming said plate and having a transverse cross-section substantially equal to said desired transverse cross-section of said half torus, said first annular plunger positioned so as to permit entry into said annular channel of said female die member and a second annular plunger for flanging said flat plate, said second annular plunger positioned so as to permit its passage along the outside of said cylindrical outer surface; said second annular plunger of said male die member being oflonger transverse height from said second base than said first annular plunger.

3. The apparatus for cold forming a half torus of claim 2 wherein said female die member further comprises a means for removing said half torus from said annular channel of said female die member.

4. The apparatus for cold forming a half torus of claim 3 wherein said means for removing said half torus is an ejection means comprising: an actuating shaft positioned along the central axis of said female die member; at least three interconnected arms adjacent to one end of said shaft and extending in a direction radially perpendicular therefrom, the outer extremity of said arms being located directly beneath said annular channel of said female die member; and a pad integrally attached to the top of each of said arms at said extremity of said arms; whereby when said actuating shaft is actuated, said pads of said arms contact and push said half torus out of said annular channel. 

1. An apparatus for cold forming a half torus of desired transverse cross-section from an annular flat plate comprising: a first base; a second base spaced from said first base; an actuating means for moving said first base toward said second base; a male die member attached to and extending from said first base toward said second base, said male die member comprising an annular flanging means for flanging said annular flat plate, and an annular cold forming means for forming said plate into a half torus of said desired cross-section, said annular cold forming means disposed radially inward from said annular flanging means and integrally related thereto, said annular flanging means being of longer transverse height from said first base than said annular cold forming means; a female die member attached to said second base and extending toward said first base, said female die member comprising a cylindrical outside surface positioned so as to permit said annular flanging means of said male die member to pass along the outside thereof, a receiving means for receiving said annular cold forming means of said male die member, and a means for locating and retaining said annular flat plate whereby when said bases are actuated, said male member and said female member engage one another such that said annular flanging means passes outside of said cylindrical outside surface and said annular cold forming means of said male member enters said receiving means of said female member, thereby causing said flat plate to be first flanged and then formed into said half torus of said desired cross-section in a single action step.
 2. An apparatus for cold forming a half torus of desired transverse cross-section from a flat annular plate comprising: a first base; a cylindrical female die member extending from said first base, said female die member having integrally related elements including a cylindrical locating surface for locating and retaining said flat plate, two cylindrical surfaces defining an annular channel of width substantially equal to the width of said desired transverse cross-section of said half torus and positioned radially outward from said locating surface, and a cylindrical outer surface positioned radially outward from said locating surface and from said annular channel; a second base; a cylindrical male die member extending from said second base, said male die member having integrally related elements including a first annular plunger for cold forming said plate and having a transverse cross-section substantially equal to said desired transverse cross-section of said half torus, said first annular plunger positioned so as to permit entry into said annular channel of said female die member and a second annular plunger for flanging said flat plate, said second annular plunger positioned so as to permit its passage along the outside of said cylindrical outer surface; said second annular plunger of said male die member being of longer transverse height from said second base than said first annular plunger.
 3. The apparatus for cold forming a half torus of claim 2 wherein said female die member further comprises a means for removing said half torus from said annular channel of said female die member.
 4. The apparatus for cold forming a half torus of claim 3 wherein said means for removing said half torus is an ejection means comprising: an actuating shaft positioned along the central axis of said female die member; at least three interconnected arms adjacent to one end of said shaft and extending in a direction radially perpendicular therefrom, the outer extremity of said arms being located directly beneath said annular channel of said female die member; and a pad integrally attached to the top of each of said arms at said extremity of said arms; whereby when said actuating shaft is actuated, said pads of said arms contact and push said half torus out of said annular channel. 